Lead study author Dr. Robert Poston of the University of Maryland Medical Center, now at Boston Medical Center, said scans taken months afterward show robotic grafts had less narrowing and fewer clots.

The researchers compared 100 consecutive patients having robotic surgery -- which allows use of a blood vessel inside the chest -- to a matched group of 100 patients with traditional "open" bypass surgery which requires a surgical incision through the sternum and leg blood vessel.

The initially higher costs of about $8,000 for robotic bypass surgery are offset by long-term savings, Poston said.

Hospital stays for robotic surgery patients averaged four days vs. seven days for "open" operation patients. In high-risk patients, the average robotic surgery stay was five days, compared to 12 days with the open technique.

Eighty-eight percent of patients with robotic bypass remained free of complications after surgery compared to 66 percent of those with the "open" operation.

The findings were presented at the meeting of the American Surgical Association in New York.